Statistical%20analysis%20of%20model-fitted%20inner-jets%20of%20the%20MOJAVE%20blazars

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Statistical analysis of model-fitted inner-jets
of the MOJAVE blazars

• Xiang Liu, Ligong Mi, et al.
• Xinjiang Astronomical Observatory
• (Former Urumqi Observatory), CAS

In JD6 Connection between radio and high energy
emission in AGNs, IAU GA
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Jet model
Marscher et al. 2008
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Two-zone inner-jet models

• We propose the two-zone inner-jet models

Zone-2 Envelop fluid
Helical jet
Zone-1 Poloidal beam
Beam jet
Two-zone model 1
two-zone model 2
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The two-fluid model

• 1, the outflow consists of an e-p plasma (the
  jet), moving at mildly relativistic speed
• 2, An e plasma (the beam) moving at highly
  relativistic speed
• 3, the magnetic field lines are parallel to the
  flow in the beam and the mixing layer,
• and are toroidal in the jet

Roland et al. 2009, see the two-zone,
spine-sheath models (Karouzos talk in this
morning)?
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The model-fit to the MOJAVE blazars cores

• The sample defined by
• 1, blazars with more than 10 years VLBA
  monitoring,
• 2, observed at gt15 epochs, good distribution in
  time.
• It consists of 104 sources, inclunding 77 quasars
  and 27 BL Lacs, in which 82 are Fermi LAT
  detected, 22 non-detected, 9 are also TeV
  sources.
• This research has made use of data from the
  MOJAVE database that is maintained by the MOJAVE
  team (Lister et al., 2009, AJ, 137, 3718)?
• http//www.physics.purdue.edu/MOJAVE/

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Example IBL 0716714
Mojave image at 15 GHz
Model-fitted inner-jet PA vs restoring beam
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The model-fit method and result

• Almost all blazars of our sample are
  core-dominated, can use an elliptical
  two-dimension Gaussian fit, also see Kovalev et
  al. (2005) Marti-Vidal et al. (2011, 2012) for
  more discussions.
• The model-fit gives peak flux density (per beam),
  PF, Position Angle of major axis, major axis and
  minor axis.
• We consider that the core' in the 15 GHz VLBA
  image is the inner-jet' rather than the true
  core. Therefore, the inner-jet can be modeled
  with an elliptic Gaussian component which its
  major axis is along with the inner-jet
  orientation or the inner-jet ridge-line on
  average,
• thus reflecting the inner-jet position angle.
  Major axis of the Gaussian can be as the
  inner-jet length scale (kovalev, et al. 2005).

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Two-zone inner-jet models

• For beam component in zone-1,
• Only correlation between PF maj is expected.
• Refered to the zone-1 dominated

For helical component in zone-2, other
correlations (PFPA, PAmaj) may be expected,
refered to the zone-2 dominated
Zone-2 Envelop fluid
Zone-1 Poloidal beam
Helical jet
Beam jet
Two-zone model 1 two-zone model 2
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64 blazars in the sample have PFmaj negative
correlation
They could be dominated by the precession/ swing
Ballistic jet in the zone-1 A geometric
beaming effect, or Outbursts with
precession/ swing
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IBL 0716714

Michgan data Vari period 5.7 yr Fan et al. 2007
Liu et al. 2012
This could be Explained with the helical
non-ballistic jet in the zone-2 A ballistic
precession/swing Beam emission Cannot explain
This correlation
Positive correlation (PF PA)?
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Non-ballistic helical jet
Ballistic jet
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The dPA (max dPA here) Is similar to that jet
ridge-line width from CJF sample Karouzos et al.
(2012), except in small dPA regiuon LAT
detected peak at higher dPA than LAT non detected
blazars, similar to Pushkarev et al.(2012)
result, with different method. Quasars peak at
smaller dPA?
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This result is generally consistent with that the
LAT detected are more variable blazars, see
Lister et al. (2009), But the quasars show no
significant different from BL Lacs in the
distribution of variabilities in PF and maj. It
has been suggested that Doppler factor is not the
sole factor that determines whether a particular
AGN is bright at ?-ray energies (Lister 2012)?
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No strong variability evolution in PF, maj and
dPA with redshift. For quasars, there seems to
be stronger variability around redshift 2.1 and a
marginal hint of wiggling variability. For BL
Lacs, because of less data and relatively low
redshift, there is a marginal peak in variability
around redshift 0.3. But these are marginal.
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Summary

• The model-fit result of the cores of 104
  blazars from the MOJAVE monitoring data, suggests
  that
• Fermi LAT-detected blazars have a wider position
  angle changes of inner-jet than LAT non-detected
  blazars, and are preferentially
• associated with higher variable blazars.
• We propose a two-zone jet model to explain the
  correlations in the model-fitted parameters, that
  the blazars in our sample are predominated by the
  beam of the inner than the jet in the outer.
• Fermi GeV gamma-ray detection rate show equally
  similar
• fraction for the innermost jet (zone-1) dominated
  and the outer jet (zone-2) blazars. But
  importantly
• TeV gamma-ray sources associate mostly with the
  outer part of inner-jet (zone-2).

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• Thank you
• For your attention!